10 Fast-Growing Annuals You Can Grow From Seed
Starting flowers from seed is one of the most rewarding parts of gardening. It’s affordable, satisfying, and gives you an incredible sense of accomplishment when you see tiny sprouts transform into blooming beauties. And if you’re like me — a bit impatient sometimes — you’ll be thrilled to know there are plenty of fast-growing annuals you can direct sow or start indoors for quick color.
Today I’m sharing 10 of my favorite fast-growing annuals that are easy to grow from seed. These are perfect for filling in flower beds, containers, or adding bursts of color throughout the season. Let’s dive in!
Fast-Growing Annuals (not an exhaustive list)
1. Zinnias
Zinnias are a must-grow in my garden every year. They’re practically foolproof, grow fast from seed, and bloom their hearts out all summer long.
Sow seeds directly into the soil after the last frost date — they germinate quickly, often within 5–7 days.
Choose from dwarf varieties for pots or tall ones for cutting gardens. Plus, the more you cut them, the more they bloom!
Tip: They love full sun and appreciate deadheading for even more flowers.
Easy Steps to Grow Zinnias
The beauty of many of these is the seeds are readily available and inexpensive!
2. Cosmos
If you’re looking for a carefree, cottage-garden feel, cosmos are your new best friend.
They grow easily from seed, thrive on neglect, and bloom just 8–10 weeks after sowing. I scatter them liberally around my garden — they’re wonderful for filling in gaps and attracting pollinators.
Tip: Don’t over-fertilize — they actually prefer lean soil, and too much nitrogen can cause more foliage than flowers.
Cosmos – A Must Have Flower
3. Sunflowers
Few things bring a smile faster than a cheerful sunflower. And good news — they’re one of the easiest seeds to grow, even for beginners.
You can direct sow sunflower seeds right into your garden after your last frost date. Some dwarf varieties (like ‘Sunspot’ or ‘Teddy Bear’) bloom in as little as 60 days!
Tip: Stagger your plantings every 2 weeks for continuous blooms into fall.
4. Nasturtiums
I adore nasturtiums for their charming, old-fashioned look — and their peppery edible leaves and flowers!
These seeds are large (perfect for kids or new gardeners) and sprout quickly, usually within a week. Nasturtiums prefer poorer soil and less fuss, making them low-maintenance champions.
Tip: Soak seeds overnight before planting to speed up germination.
5. Sweet Peas
If you love old-fashioned charm and heavenly fragrance, you must grow sweet peas.
They’re easy to start from seed and grow quickly once the weather warms a bit. Sweet peas bring romantic beauty to trellises, fences, and obelisks with their delicate, fluttery blooms.
Tip: Soak seeds overnight before planting to speed up germination, and plant them early — they thrive in cooler spring temperatures.
Sweet Peas for a Perfumed Space
6. Sweet Alyssum
Want quick ground cover or a sweet-smelling carpet of blooms? Sweet alyssum is the answer.
It germinates in just 5–10 days and blooms in under 2 months. I like to tuck it along paths and in between pavers for a soft, romantic look.
Tip: Shear it back when it gets leggy — it will bounce right back with fresh blooms.
Note: Tiny Tim Alyssum usually has not needed shearing back, you can find the seeds here!
7. Bachelor’s Buttons (Cornflower)
Bachelor’s buttons are an old-fashioned favorite and for good reason — they’re hardy, fast-growing, and charming.
Sow seeds directly into the ground — they don’t love transplanting — and enjoy vivid blue (and sometimes pink, white, or purple) blooms in about 8–10 weeks.
Tip: Bachelor’s buttons are perfect for cutting gardens and dry beautifully for arrangements.
8. Marigolds
Marigolds might be one of the most beginner-friendly annuals ever. They’re quick to germinate, bloom reliably, and are tough enough to handle heat and drought.
Whether you choose tiny French marigolds or the big, showy African types, they add sunny splashes of color all season.
Tip: Start seeds indoors for earlier blooms or sow directly outside after frost danger passes.
9. Morning Glories
If you need fast vertical interest, morning glories are the ticket.
Plant them near a fence, trellis, or obelisk and watch them climb. They grow like a dream from seed (especially if you nick the seed coat with a nail file first), and bloom in vibrant shades of blue, purple, pink, and white.
Tip: Be patient — they need warm soil to really take off, but once they do, there’s no stopping them!
10. Clarkia
Note: there are two types Clarkia elegans and Clarkia amoena
This pretty little flower is often overlooked but deserves more attention.
Clarkia seeds grow quickly, thrive in cooler temps, and produce masses of delicate, papery blooms in soft pastels and bright pinks.
Read the seed packet for more specific growing instructions for each type!
Tip: Direct sow early in the season — they don’t like to be transplanted.
Final Thoughts
There you have it — 10 fast-growing annuals you can easily grow from seed! Whether you want bold color, sweet fragrance, or whimsical charm, there’s something on this list for every garden style.
Starting from seed isn’t just economical — it gives you a garden full of life, from that first tiny sprout to armloads of beautiful blooms.
Give a few (or all!) of these a try this season and enjoy the satisfaction of growing your own colorful paradise.
10 More Fast-Growing Annuals:
- Poppies — Especially Shirley and California poppies; direct sow for quick spring color.
- Larkspur — Cool-season lover; sow early for beautiful spiky blooms.
- Love-in-a-Mist (Nigella) — Airy, whimsical flowers that sprout and bloom fast.
- Phlox (Annual Phlox/Phlox drummondii) — Quick to germinate and bloom with bright colors.
- Amaranth — Fast-growing with stunning foliage and dramatic seedheads.
- Dianthus (Annual Pink) — Sweetly scented, blooms in about 8 weeks.
- Coreopsis (Annual varieties) — Sunny yellow blooms that sprout and flower fast.
- Snapdragons (Dwarf or Early Types) — Some varieties bloom quickly from seed, especially in cool weather.
- Celosia — Vibrant plumes or crests in bright summer colors; quick to establish and bloom.
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I wish you quick blooms and Happy Gardening!
Hi, I’m Pamela
My goal is to cultivate the love of gardening and help make your gardening life more enjoyable!
